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LGE Internal Use Only
Copyright © 011 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
3.12.1 Current Source LED Driver for LCD Display
There are four current source LED drivers in the RT8966.
These current sources can be programmed via I2C in the following control registers, Enable and LED Set.
These registers include each driver's enable/disable control, source current control, and LED brightness
dimming.
The RT8966 provides a constant current for the white LEDs. Each channel supports up to 30mA current and
regulates a constant current for uniform intensity. In order to maintain LED constant current, the input
voltage must provide the required LED forward voltage and current source dropout voltage. If the forward
voltage of the white LEDs is 3.3V, the input voltage should be higher than 3.4V to provide enough voltage
headroom for maintaining constant brightness.
Figure 3.12.1. RT8966GQW CIRCUIT DIAGRAM
3.12 MINI ABB Interface
The RT8966 is an analog subsystem which includes a linear charger, 4 LDOs, a 4-CH current source, and a
multiplexer for USB, UART, microphone, stereo and audio on a single mini/micro USB connector.
CAM_AVDD
DNI
C252
2.2u
C230
50
2
BF
00
6
CAM_IOVDD
600
FB202
10K
R242
VBAT
1V8_VDD
100K
R228
C246
1u
C243
DNI
L202
1.5n
L201
1.5n
VBUS_EXT
2.2K
R235
600
FB204
0.1u
C248
2.2u
C241
120
FB203
VBUS
1V8_VDD
1u
C231
0.1u
C247
2.2u
C242
1u
C240
CAM_DVDD
39p
C251
39p
C250
1u
C239
39p
C249
FM_LNA_EN
U202
RT8966AGQW
33
82
27
26
13
25
11
01
24
23
13
22
92
21
20
14
12
7
2
9
5
32
19
18
17
8
03
6
16
4
3
15
1
1T
U
O
AUD1
VIN
3T
U
O
AUD2
1
D
N
G
L
C
S
2
D
EL
MIC
CAP
RES
DSS
4T
U
O
3
D
EL
2T
U
O
1
D
EL
DP
U2
UID
D+
A
D
S
D-
\T
NI
VBUS1
VBUS2
4
D
EL
DN
VBAT1
U1
VBAT2
EXPDET
2
D
N
G
D
N
G
P
UART_RX
UART_TX
USB_DM
USB_DP
HS_MIC_P
HS_MIC_N
I2C_SDA
I2C_SCL
MINI_ABB_INT_N
2
D
E
L
M
3
D
E
L
M
1
D
EL
M
MUIC_IO_M
HS_OUT_R
MUIC_ID
MUIC_IO_P
HS_OUT_L